In some deep and highly deviated wellbores, power is needed for many operations, including, for example, conveying evaluation tools, taking formation cores, operating valves, milling plugs, and other mechanical operations. Electrical motors (such as direct current powered motors) are commonly used for such operations. Due to the depth of some wells in which motors must operate and the length of cables needed to power such motors, motor performance is severely diminished.
In oil wells and with cables that may be 30,000 feet or longer, motors must operate continuously at the peak power the cable can convey, and traditional motor control, based on maintaining either velocity or torque, is not appropriate for reliable and efficient operation. Similarly, actuators, power converters and signal generators may cause a demand of peak power above what the power delivery system can provide when transient the load impedance changes while operating at or near maximum power. Peak power limitations similar to those described for long cables also exist in battery powered systems, where peak power demands can shorten battery autonomy.